1. Field of the Invention
The present invention relates to the biodegradable control of bacterial cellulose by radiation technology and an absorbable periodontal tissue and bone regeneration material using the same.
2. Description of the Related Art
Cellulose is a renewable and the most abundant resource in the natural world, which is a polysaccharide composed of glucose in β-1,4 linkage. Cellulose is not only used in various industrial fields including paper and pulp industry but also applied to a variety of industrial fields. Thus, the consumption of cellulose is increasing significantly. Cellulose has a strong resistance against chemicals and microorganism attack, so that it is used as a raw material for the production of paper and clothes. Ether derivative is used as a raw material of rayon and nitroester is used as a raw material of gunpowder (non-patent reference 1-3).
The generation of cellulose is mainly accomplished in plants but is possibly achieved in bacteria. A general plant fiber is composed of cellulose, hemicellulose, and lignin. In the meantime, the bacterial cellulose is composed of only pure cellulose so that it does not need to be purified additionally (non-patent reference 4). According to the previous studies, the major bacterium that can synthesize cellulose is Acetobacter xylinum. In addition, numbers of bacteria genera including Agrobacterium, Pseudomonas, Rhizobium, and Sarcina are known to produce cellulose (non-patent reference 5). It was first reported by Brown in 1886 that cellulose could be produced not only in plants but also in microorganisms such as acetic acid bacteria. The strain that can produce bacterial cellulose with the highest yield is Acetobacter xylinum which is gram-negative aerobic microorganism, because of which it has long been a target of study about bacterial cellulose (non-patent reference 6).
The potential of the bacterial cellulose for being applied to a variety of fields, due to its unique physiochemical and mechanical properties, was reported earlier (non-patent reference 4). The most efficient producing strain of bacterial cellulose is the gram negative Acetobacter xylinum, more specifically Gluconacetobacter xylinus (non-patent reference 7). The strain exists as a single or a couple or in chains, and is reproduced by binary fission, but does not form endospores. In a limited condition, A. xylinum displays the degenerated form, which is often found in swollen or extended filament. The proper temperature for the growth of Acetobacter xylinum is 25˜30° C. and the proper pH is 5.4˜6.2.
Unlike the plant-derived cellulose, bacterial cellulose is the pure cellulose that does not include any impurities such as hemicelluloses, pectin, lignin, and biogenic products, so that high purity cellulose can be purified with a small amount of energy and materials (non-patent reference 8). The bacterial cellulose has a three-dimensional network structure formed by hydrogen bonds of nanofibrils (20˜50 nm), and has high tensile strength, water retention power, and Young's modulus, so that it can be applied to high-performance diaphragm, high-quality paper, cosmetics, and dietary food, etc. According to the advancement of recent biomedical materials, the bacterial cellulose is also tried in wound dressing and drug delivery systems (DDS) using natural polymers and synthetic polymers. The bacterial cellulose generated by some bacteria is excellent in its physical and biological properties, which favors the application to the field of biomedicine. The bacterial cellulose produced by Acetobacter xylinum has been recognized as a high-value product in the field of biotechnology and has been successfully used as burn wound dressing (non-patent reference 9).
The absorbable periodontal tissue regeneration material is to shield the area of periodontal bone regeneration to induce the regeneration of damaged periodontal bone. Collagen was conventionally used as the material. However, a collagen membrane is easily degraded before the regeneration of periodontal bone is completed. In addition to the high price, the collagen membrane cannot guarantee the successful bond formation.
The present inventors succeeded in maintaining the shield effect with the bacterial cellulose until the periodontal tissue and bone were completely regenerated by using radiation technology, precisely by cutting the linkage of cellulose physically to regulate biodegradation so that the biodegradation speed could be slowed compared with the conventional collagen membrane, leading to the completion of the invention which can bring high economic effect as well since the inventors used the low-priced bacterial cellulose.